Introduction: Replacing a Throttle Position Sensor on a Jeep Wrangler

By www.gdhenson.com
About: Software QA Test Engineer/Technical Writer

It's always best to do any work yourself, then you can be sure it was done right, plus it will save you a considerable amount of cash. If at all possible, I try to do all required minor repairs to any of our out of warranty vehicles. In this case it's our 2003 Jeep Wrangler TJ.

The check engine light came on a couple of weeks ago with the code: PO122 (throttle body sensor/switch) 

Details:

P0122 - Set Condition: Throttle Position Sensor voltage at the PCM is lower than 0.1 of a volt for 1.3 seconds.

POSSIBLE CAUSES
TP SENSOR SWEEP
INTERMITTENT CONDITION
(K7) 5-VOLT SUPPLY CIRCUIT OPEN
(K7) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
TP SENSOR
(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO (K4) SENSOR GROUND CIRCUIT
TCM INTERNALLY SHORTED THROTTLE POSITION SIGNAL CIRCUIT
PCM


Step 1: Overview

This is a pretty straight forward replacement. I checked around with a few shops in my local area and the price to replace this part was anywhere from $100.00 - $180

Since replacing the TPS I've noticed an increase in MPGs (around a 10-15% increase) as well as better acceleration on hills and while passing.



Step 2: Details, Parts and Tools

Symptoms: Check engine light is on with an output code of PO122. Engine revs to high RPMs when engine is started. 

Cost: $25.00 - $34.99 (AutoZone and Napa both keep these in stock)

Tools needed: Ratchet set with torx sockets/bits and a strong thumb

Time: 25 minutes

Prep: Disconnect the battery. It's is recommended that you always disconnect the battery when doing any kind of work on the electrical systems of any vehicle. You also might want to wait for your engine to cool down if you have been driving the vehicle recently, unless you like getting burnt.

Step 3: Locating and Identifying the TPS

The TPS is held in place by two torx screws and is connected to the vehicles computer by a cream colored modular plug. It is located on the top of the engine next to the air intake.


Step 4: Remove Modular Plug

Remove the modular plug before removing the 2 screws on the TPS. The locking clip is on the top of the plug so a firm push with your thumb should do the trick. I had to wiggle the plug a few times as well as re-seat it before the clip would disengage.

Step 5: Remove the Two Torx Screws Holding the TPS In

The next thing you need to do is remove the two Torx screws holding the TPS in. There is a screw on each side of the TPS, one on the drivers side and another on the passengers side. The two holding mine in when in there pretty tight, be sure to make sure the Torx bit is firmly seated in the Torx screw before you start to unscrew to avoid stripping the screw head.

Step 6: Lining Up the New TPS

There is a small pin that sticks out from the throttle body that interfaces with the TPS, it is visible once the old TPS is removed. This pin sticks into the hourglass shaped area in the TPS. Once you have the TPS seated you will need to turn the TPS clockwise very slightly to get the pin to slip into the hourglass shaped area, when it does turn it back to line up with the screw holes.

Install the two new screws that came with the TPS and plug in the modular plug. Reconnected your battery and you should be good to go.